linux-kernel - [PATCH 3.18 31/39] brcmfmac: Make skb header writable before use

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Message-Id: <20170511130244.588789359@linuxfoundation.org>
Date:   Thu, 11 May 2017 15:03:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        James Hughes <james.hughes@...pberrypi.org>,
        Arend van Spriel <arend.vanspriel@...adcom.com>,
        Kalle Valo <kvalo@...eaurora.org>
Subject: [PATCH 3.18 31/39] brcmfmac: Make skb header writable before use

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: James Hughes <james.hughes@...pberrypi.org>

commit 9cc4b7cb86cbcc6330a3faa8cd65268cd2d3c227 upstream.

The driver was making changes to the skb_header without
ensuring it was writable (i.e. uncloned).
This patch also removes some boiler plate header size
checking/adjustment code as that is also handled by the
skb_cow_header function used to make header writable.

Signed-off-by: James Hughes <james.hughes@...pberrypi.org>
Acked-by: Arend van Spriel <arend.vanspriel@...adcom.com>
Signed-off-by: Kalle Valo <kvalo@...eaurora.org>
Signed-off-by: Arend van Spriel <arend.vanspriel@...adcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/brcm80211/brcmfmac/dhd_linux.c |   19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

--- a/drivers/net/wireless/brcm80211/brcmfmac/dhd_linux.c
+++ b/drivers/net/wireless/brcm80211/brcmfmac/dhd_linux.c
@@ -213,22 +213,13 @@ static netdev_tx_t brcmf_netdev_start_xm
 		goto done;
 	}
 
-	/* Make sure there's enough room for any header */
-	if (skb_headroom(skb) < drvr->hdrlen) {
-		struct sk_buff *skb2;
-
-		brcmf_dbg(INFO, "%s: insufficient headroom\n",
+	/* Make sure there's enough writable headroom*/
+	ret = skb_cow_head(skb, drvr->hdrlen);
+	if (ret < 0) {
+		brcmf_err("%s: skb_cow_head failed\n",
 			  brcmf_ifname(drvr, ifp->bssidx));
-		drvr->bus_if->tx_realloc++;
-		skb2 = skb_realloc_headroom(skb, drvr->hdrlen);
 		dev_kfree_skb(skb);
-		skb = skb2;
-		if (skb == NULL) {
-			brcmf_err("%s: skb_realloc_headroom failed\n",
-				  brcmf_ifname(drvr, ifp->bssidx));
-			ret = -ENOMEM;
-			goto done;
-		}
+		goto done;
 	}
 
 	/* validate length for ether packet */